Most industrial aqueous systems contain dissolved alkaline earth and transition metal cations such as calcium, magnesium, iron and the like, as well as various anions such as bicarbonate, carbonate, sulfate, and the like. When the concentration of the various combinations of these cations and anions exceeds the solubility of their reaction products, these reaction products will tend to precipitate out of solution until their product solubility concentrations are no longer exceeded. The deposits formed by the precipitation of these reaction products onto the surfaces of industrial aqueous systems is known as scale.
The precipitation of calcium carbonate is by far the most common form of scale in industrial aqueous systems. This occurs when the ionic product of calcium and carbonate exceeds the solubility of calcium carbonate, and a solid phase of calcium carbonate forms.
The formation of scale in industrial aqueous systems represents a major problem since it reduces heat transfer efficiency on heat exchange surfaces, induces or leads to increased corrosion in the system and reduces flow of the water through the system. The addition of inorganic phosphates, and more recently organic polymers, such as polyacrylates, to aqueous systems is known to prevent or inhibit scale formation. However, not all polymers have been effective for scale inhibition.
In general, the problem of the prior art polymeric scale inhibitors involves solubility and/or the ability to form strong complexes with scale forming salts. The present invention is directed to certain novel N-functionalized polyallylamines which can be tailored to control both complexation and solubility.